Tonight, we have a rare look into the mind of a serial conman. Just 18, the young florida man talked his way into an emergency room to treat patients and posed as a cop behind the wheel of a cruiser. After his arrest, he spoke to police for three hours and tonight, abc's matt gutman brings us inside that interrogation room. ♪ Come fly with me ♪ Reporter: In "catch me if you CAN," leonardo DiCaprio played the world's most infamous con artist, swavly impersonating a pilot. And a doctor. Police say 17-year-old matthew scheidt also masqueraded as a medical professional, until he got caught. In this just-released video, he tells interrogators he even administered cpr to a patient, after a real doctor left the room. He said, can you take over cpr? I started doing cpr for a minute, two minutes, while he went to get medication. He came back in. The only reason why i did do it was because there was nobody else there. And I'm not going to let her die. Reporter: And wearing scrubs and a lab coat, he kept going back for days. It becomes like an addiction. The rush is so high when they get away with it, they want that feeling again and again. Reporter: So it was for frank abegnale, the inspiration behind "catch me if you can." Impersonating a doctor, he actually wrote on patient's charts. A real pilot actually handed him control of a plane during a commercial flight. The pilot uniform always made me feel -- feel good. It gave me respect and people looked at me differently. Made me believe I was somebody. Allowed me to, of course, meet women. Reporter: So how do these imposters get away with it? Psychologists call it the halo effect. People standing around in scrubs, maybe a lab coat, they seem to have authority. Experts say if you suspect someone is an imposture all you have to do is ask them a couple of questions. That's how scheidt got busted. He was cruising around miami allegedly posing as a cop. Matt gutman, abc news, miami. And he's in some real trouble now.

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